Highly active antiretrovial therapy (HAART) has extended survival for many people infected with human immunodeficiency virus (HIV). As a result, these individuals are experiencing morbidity and mortality from other infections or co-morbid diseases that, prior to HAART, patients did not live long enough to confront. Consequently we believe that we are in the midst of something of a paradigm shift in which thinking about, and managing HIV infection as a chronic illness, will shift to a focus on HIV infection as a co-morbid medical condition that must be clinically managed, and psychosocially adjusted to, alongside one or more other signficant chronic illnesses or conditions. In many ways co-infection with hepatitis C (HCV) exemplifies the new paradigm. It is a co-morbidity that affects approximately a third of all HIV+ persons in the US and upwards of 80% of HIV+ injecting drug users (IDUs) who have been injecting for a number of years. Moreover, HCV impacts all age groups of HIV+ adults. While there has been a rapid proliferation of articles in the medical literature on HIV/HCV co-infection, the problems of living with co-infection have been virtually overlooked in the psychosocial and behavioral literature on HIV/AIDS. Yet this population promises to be one of growing importance, both because it will be at the center of two epidemics, the AIDS epidemic and the "shadow epidemic" of HCV infection - and because it is representative of the growing phenomenon of HIV+ individuals who, as survival continues to extend, will simultaneously be living and coping with another serious chronic illness or condition. Co-infected patients also present many challenges for physicians as they simultaneously manage two serious viral infections with often, unpredictable disease trajectories. To begin addressing these important gaps in the extant HIV/AIDS psychosocial literature, we propose to qualitatively investigate how co-infection with HCV impedes or complicates the mastery of several key illness-related adaptive tasks that HIV+ individuals confront, as well as to identify any unique adaptive challenges that it poses. The study sample will be composed of 140 HIV/HCV-co-infected adults with a history of injecting drug use. To begin to understand how the challenges they face in caring for co-infected patients impact patient adjustment, all 14 physicians treating patients at the AIDS clinics from which the patient sample will be recruited will also be interviewed.